Showing papers by "Charles A. Dinarello published in 2017"

A guiding map for inflammation

Abstract: Biologists, physicians and immunologists have contributed to the understanding of the cellular participants and biological pathways involved in inflammation. Here, we provide a general guide to the cellular and humoral contributors to inflammation as well as to the pathways that characterize inflammation in specific organs and tissues.

Myeloid-derived miR-223 regulates intestinal inflammation via repression of the NLRP3 inflammasome

Abstract: MicroRNA (miRNA)-mediated RNA interference regulates many immune processes, but how miRNA circuits orchestrate aberrant intestinal inflammation during inflammatory bowel disease (IBD) is poorly defined. Here, we report that miR-223 limits intestinal inflammation by constraining the nlrp3 inflammasome. miR-223 was increased in intestinal biopsies from patients with active IBD and in preclinical models of intestinal inflammation. miR-223(-/y) mice presented with exacerbated myeloid- driven experimental colitis with heightened clinical, histopathological, and cytokine readouts. Mechanistically, enhanced NLRP3 inflammasome expression with elevated IL-1 beta was a predominant feature during the initiation of colitis with miR-223 deficiency. Depletion of CCR2(+) inflammatory monocytes and pharmacologic blockade of IL-1 beta or NLRP3 abrogated this phenotype. Generation of a novel mouse line, with deletion of the miR-223 binding site in the NLRP3 3'untranslated region, phenocopied the characteristics of miR-223(-/y) mice. Finally, nanoparticle-mediated overexpression of miR-223 attenuated experimental colitis, NLRP3 levels, and IL-1 beta release. Collectively, our data reveal a previously unappreciated role for miR-223 in regulating the innate immune response during intestinal inflammation.

Alarmins: Feel the Stress.

Abstract: Over the last decade, danger-associated molecular pattern molecules, or alarmins, have been recognized as signaling mediators of sterile inflammatory responses after trauma and injury. In contrast with the accepted passive release models suggested by the "danger hypothesis," it was recently shown that alarmins can also directly sense and report damage by signaling to the environment when released from live cells undergoing physiological stress, even without loss of subcellular compartmentalization. In this article, we review the involvement of alarmins such as IL-1alpha, IL-33, IL-16, and high-mobility group box 1 in cellular and physiological stress, and suggest a novel activity of these molecules as central initiators of sterile inflammation in response to nonlethal stress, a function we denote "stressorins." We highlight the role of posttranslational modifications of stressorins as key regulators of their activity and propose that targeted inhibition of stressorins or their modifiers could serve as attractive new anti-inflammatory treatments for a broad range of diseases.

Uric acid priming in human monocytes is driven by the AKT–PRAS40 autophagy pathway

Abstract: Metabolic triggers are important inducers of the inflammatory processes in gout. Whereas the high serum urate levels observed in patients with gout predispose them to the formation of monosodium urate (MSU) crystals, soluble urate also primes for inflammatory signals in cells responding to gout-related stimuli, but also in other common metabolic diseases. In this study, we investigated the mechanisms through which uric acid selectively lowers human blood monocyte production of the natural inhibitor IL-1 receptor antagonist (IL-1Ra) and shifts production toward the highly inflammatory IL-1β. Monocytes from healthy volunteers were first primed with uric acid for 24 h and then subjected to stimulation with lipopolysaccharide (LPS) in the presence or absence of MSU. Transcriptomic analysis revealed broad inflammatory pathways associated with uric acid priming, with NF-κB and mammalian target of rapamycin (mTOR) signaling strongly increased. Functional validation did not identify NF-κB or AMP-activated protein kinase phosphorylation, but uric acid priming induced phosphorylation of AKT and proline-rich AKT substrate 40 kDa (PRAS 40), which in turn activated mTOR. Subsequently, Western blot for the autophagic structure LC3-I and LC3-II (microtubule-associated protein 1A/1B-light chain 3) fractions, as well as fluorescence microscopy of LC3-GFP-overexpressing HeLa cells, revealed lower autophagic activity in cells exposed to uric acid compared with control conditions. Interestingly, reactive oxygen species production was diminished by uric acid priming. Thus, the Akt-PRAS40 pathway is activated by uric acid, which inhibits autophagy and recapitulates the uric acid-induced proinflammatory cytokine phenotype.

Interleukin-37 suppresses the osteogenic responses of human aortic valve interstitial cells in vitro and alleviates valve lesions in mice.

Abstract: Calcific aortic valve disease is a chronic inflammatory process, and aortic valve interstitial cells (AVICs) from diseased aortic valves express greater levels of osteogenic factors in response to proinflammatory stimulation. Here, we report that lower cellular levels of IL-37 in AVICs of diseased human aortic valves likely account for augmented expression of bone morphogenetic protein-2 (BMP-2) and alkaline phosphatase (ALP) following stimulation of Toll-like receptor (TLR) 2 or 4. Treatment of diseased AVICs with recombinant human IL-37 suppresses the levels of BMP-2 and ALP as well as calcium deposit formation. In mice, aortic valve thickening is observed when exposed to a TLR4 agonist or a high fat diet for a prolonged period; however, mice expressing human IL-37 exhibit significantly lower BMP-2 levels and less aortic valve thickening when subjected to the same regimens. A high fat diet in mice results in oxidized low-density lipoprotein (oxLDL) deposition in aortic valve leaflets. Moreover, the osteogenic responses in human AVICs induced by oxLDL are suppressed by recombinant IL-37. Mechanistically, reduced osteogenic responses to oxLDL in human AVICs are associated with the ability of IL-37 to inhibit NF-κB and ERK1/2. These findings suggest that augmented expression of osteogenic factors in AVICs of diseased aortic valves from humans is at least partly due to a relative IL-37 deficiency. Because recombinant IL-37 suppresses the osteogenic responses in human AVICs and alleviates aortic valve lesions in mice exposed to high fat diet or a proinflammatory stimulus, IL-37 has therapeutic potential for progressive calcific aortic valve disease.

Interleukin 37 reverses the metabolic cost of inflammation, increases oxidative respiration, and improves exercise tolerance.

Abstract: IL-1 family member interleukin 37 (IL-37) has broad antiinflammatory properties and functions as a natural suppressor of innate inflammation. In this study, we demonstrate that treatment with recombinant human IL-37 reverses the decrease in exercise performance observed during systemic inflammation. This effect was associated with a decrease in the levels of plasma and muscle cytokines, comparable in extent to that obtained upon IL-1 receptor blockade. Exogenous administration of IL-37 to healthy mice, not subjected to an inflammatory challenge, also improved exercise performance by 82% compared with vehicle-treated mice (P = 0.01). Treatment with eight daily doses of IL-37 resulted in a further 326% increase in endurance running time compared with the performance level of mice receiving vehicle (P = 0.001). These properties required the engagement of the IL-1 decoy receptor 8 (IL-1R8) and the activation of AMP-activated protein kinase (AMPK), because both inhibition of AMPK and IL-1R8 deficiency abrogated the positive effects of IL-37 on exercise performance. Mechanistically, treatment with IL-37 induced marked metabolic changes with higher levels of muscle AMPK, greater rates of oxygen consumption, and increased oxidative phosphorylation. Metabolomic analyses of plasma and muscles of mice treated with IL-37 revealed an increase in AMP/ATP ratio, reduced levels of proinflammatory mediator succinate and oxidative stress-related metabolites, as well as changes in amino acid and purine metabolism. These effects of IL-37 to limit the metabolic costs of chronic inflammation and to foster exercise tolerance provide a rationale for therapeutic use of IL-37 in the treatment of inflammation-mediated fatigue.

NLRP1 promotes tumor growth by enhancing inflammasome activation and suppressing apoptosis in metastatic melanoma.

Abstract: NLRP1 promotes tumor growth by enhancing inflammasome activation and suppressing apoptosis in metastatic melanoma

IL-1 Inhibition and Vascular Function in CKD.

Abstract: Vascular endothelial dysfunction and increased arterial stiffness contribute to increased cardiovascular risk in patients with CKD who exhibit chronic systemic inflammation. Because chronic inflammation contributes to vascular dysfunction, blocking inflammation may reduce cardiovascular risk in patients with CKD. In a two-site, double-blind trial, we randomized 42 adult patients with stage 3-4 CKD who were already receiving optimal background therapy to receive either IL-1 trap rilonacept or placebo for 12 weeks. Coprimary end points included change in brachial artery flow-mediated dilation (FMDBA) and aortic pulse-wave velocity (aPWV) after 4, 8, and 12 weeks. Exploratory end points included change in high-sensitivity C-reactive protein (hsCRP), FMDBA after acute ascorbic acid infusion, and vascular endothelial cell protein expression of NADPH oxidase. Participants were 63±11 (mean±SD) years of age and 24% were women; mean eGFR was 38±13 ml/min per 1.73 m2 Compared with placebo, rilonacept improved FMDBA (baseline: 3.36%±2.06% [mean±SD], 12 weeks: 2.45%±2.29% with placebo and baseline: 3.75%±3.12%, 12 weeks: 4.86%±3.20% with rilonacept; P<0.01), without changing aPWV (P=0.56). Rilonacept also reduced hsCRP levels (median [interquartile range]) (baseline: 4.60 [1.90-8.22] mg/L, 12 weeks: 2.16 [0.92-7.38] mg/L; P<0.01) and endothelial cell NADPH oxidase expression (P<0.05). Acute infusion of ascorbic acid to inhibit superoxide production associated with a nonsignificant trend toward increased FMDBA in the placebo group (P=0.07) but not the rilonacept group (P=0.56). Rilonacept was well tolerated (five adverse events versus two with placebo). In conclusion, treatment with an IL-1 trap improved FMDBA without changing aPWV and reduced systemic inflammation in patients with CKD.

Interleukin-1 as a mediator of fatigue in disease: a narrative review

Abstract: Fatigue is commonly reported in a variety of illnesses, and it has major impact on quality of life. Previously, it was thought that fatigue originates in the skeletal muscles, leading to cessation of activity. However, more recently, it has become clear that the brain is the central regulator of fatigue perception. It has been suggested that pro-inflammatory cytokines, especially interleukin-1 alpha (IL-1α) and interleukin-1 beta (IL-1β), play a prominent role in the development of central fatigue, and several studies have been performed to elucidate the connection between inflammation and these central processes. In this narrative review, mechanisms of action of IL-1 are described, with special attention to its effect on the central nervous system. In addition, we present a summary of studies that (i) investigated the relationship between circulating IL-1α and IL-1β and fatigue severity and/or (ii) evaluated the effect of inhibiting IL-1 on fatigue. We aim to improve the understanding of fatigue in both inflammatory and non-inflammatory illnesses, which could help develop strategies to treat fatigue more effectively. Reviewing the studies that have been performed, it appears that there is a limited value of measuring circulating IL-1. However, inhibiting IL-1 has a positive effect on severe fatigue in most studies that have been conducted.

Interleukin-1 Receptor Blockade Rescues Myocarditis-Associated End-Stage Heart Failure

Abstract: Support measures currently represent the mainstay of treatment for fulminant myocarditis, while effective and safe anti-inflammatory therapies remain an unmet clinical need. However, clinical and experimental evidence indicates that inhibition of the pro-inflammatory cytokine interleukin 1 (IL-1) is effective against both myocardial inflammation and contractile dysfunction. We thus evaluated treatment with the IL-1 receptor antagonist anakinra in a case of heart failure secondary to fulminant myocarditis. A 65-year-old man with T cell lymphoma developed fulminant myocarditis presenting with severe biventricular failure and cardiogenic shock requiring admittance to the Intensive Care Unit and mechanical circulatory and respiratory support. Specifically, acute heart failure and cardiogenic shock were initially treated with non-invasive ventilation and mechanical circulatory support with an intra-aortic balloon pump (IABP). Nevertheless, cardiac function deteriorated further, and there were no signs of improvement. Treatment with anakinra, the recombinant form of the naturally occurring IL-1 receptor antagonist, was started at a standard subcutaneous dose of 100 mg/day. We observed a dramatic clinical improvement within 24 hrs of initiating anakinra. Prompt, progressive amelioration of cardiac function allowed weaning from mechanical circulatory and respiratory support within 72 hrs of anakinra administration. Recent studies point at inhibition of IL-1 activity as an attractive treatment option for both myocardial inflammation and contractile dysfunction. Furthermore, IL-1 receptor blockade with anakinra is characterized by an extremely rapid onset of action and remarkable safety, and may thus be suitable for the treatment of patients critically ill with myocarditis.

Abnormal epigenetic changes during differentiation of human skeletal muscle stem cells from obese subjects.

Abstract: Human skeletal muscle stem cells are important for muscle regeneration. However, the combined genome-wide DNA methylation and expression changes taking place during adult myogenesis have not been described in detail and novel myogenic factors may be discovered. Additionally, obesity is associated with low relative muscle mass and diminished metabolism. Epigenetic alterations taking place during myogenesis might contribute to these defects. We used Infinium HumanMethylation450 BeadChip Kit (Illumina) and HumanHT-12 Expression BeadChip (Illumina) to analyze genome-wide DNA methylation and transcription before versus after differentiation of primary human myoblasts from 14 non-obese and 14 obese individuals. Functional follow-up experiments were performed using siRNA mediated gene silencing in primary human myoblasts and a transgenic mouse model. We observed genome-wide changes in DNA methylation and expression patterns during differentiation of primary human muscle stem cells (myoblasts). We identified epigenetic and transcriptional changes of myogenic transcription factors (MYOD1, MYOG, MYF5, MYF6, PAX7, MEF2A, MEF2C, and MEF2D), cell cycle regulators, metabolic enzymes and genes previously not linked to myogenesis, including IL32, metallothioneins, and pregnancy-specific beta-1-glycoproteins. Functional studies demonstrated IL-32 as a novel target that regulates human myogenesis, insulin sensitivity and ATP levels in muscle cells. Furthermore, IL32 transgenic mice had reduced insulin response and muscle weight. Remarkably, approximately 3.7 times more methylation changes (147,161 versus 39,572) were observed during differentiation of myoblasts from obese versus non-obese subjects. In accordance, DNMT1 expression increased during myogenesis only in obese subjects. Interestingly, numerous genes implicated in metabolic diseases and epigenetic regulation showed differential methylation and expression during differentiation only in obese subjects. Our study identifies IL-32 as a novel myogenic regulator, provides a comprehensive map of the dynamic epigenome during differentiation of human muscle stem cells and reveals abnormal epigenetic changes in obesity.

IL-37 Suppresses MyD88-mediated Inflammatory Responses in Human Aortic Valve Interstitial Cells

Abstract: Calcific aortic valve disease (CAVD) is common among the elderly, and aortic valve interstitial cells (AVICs) exhibit unique inflammatory and osteogenic responses to proinflammatory stimulation, which plays an important role in valvular fibrosis and calcification. Thus, suppression of AVIC proinflammatory response may have therapeutic utility for the prevention of CAVD progression. Interleukin (IL)-37, an antiinflammatory cytokine, reduces tissue inflammation. This study aimed to test the hypothesis that IL-37 suppresses human AVIC inflammatory responses to Toll-like receptor (TLR) agonists. Human AVICs were exposed to Pam3CSK4, poly(I:C) and lipopolysaccharide in the presence and absence of recombinant human IL-37. Stimulation of TLR4 increased the production of intercellular adhesion molecule-1, IL-6, IL-8 and monocyte chemoattractant protein-1. Knockdown of myeloid differentiation factor 88 (MyD88) or TIR-domain-containing adaptor-inducing interferon-β differentially affected inflammatory mediator production following TLR4 stimulation. IL-37 reduced production of these inflammatory mediators induced by TLR4. Moreover, knockdown of IL-37 enhanced induction of these mediators by TLR4. IL-37 also suppressed inflammatory mediator production induced by the MyD88-dependent TLR2, but had no effect on the inflammatory responses to the TRIF-dependent TLR3. Furthermore, IL-37 inhibited NF-κB activation induced by TLR2 or TLR4 through a mechanism dependent of IL-18 receptor α-chain. Activation of TLR2, TLR3 or TLR4 upregulates the production of inflammatory mediators in human AVICs. IL-37 suppresses MyD88-mediated responses to reduce inflammatory mediator production following stimulation of TLR2 and TLR4. This antiinflammatory cytokine may be useful for suppression of aortic valve inflammation elicited by MyD88-dependent TLR signaling.

Cytokines and microbicidal molecules regulated by IL-32 in THP-1-derived human macrophages infected with New World Leishmania species.

Abstract: Background Interleukin-32 (IL-32) is expressed in lesions of patients with American Tegumentary Leishmaniasis (ATL), but its precise role in the disease remains unknown. Methodology/Principal findings In the present study, silencing and overexpression of IL-32 was performed in THP-1-derived macrophages infected with Leishmania (Viannia) braziliensis or L. (Leishmania) amazonensis to investigate the role of IL-32 in infection. We report that Leishmania species induces IL-32γ, and show that intracellular IL-32γ protein production is dependent on endogenous TNFα. Silencing or overexpression of IL-32 demonstrated that this cytokine is closely related to TNFα and IL-8. Remarkably, the infection index was augmented in the absence of IL-32 and decreased in cells overexpressing this cytokine. Mechanistically, these effects can be explained by nitric oxide cathelicidin and β-defensin 2 production regulated by IL-32. Conclusions Thus, endogenous IL-32 is a crucial cytokine involved in the host defense against Leishmania parasites.

Cytokine Inhibition in Patients With Chronic Fatigue Syndrome: A Randomized Trial

Abstract: Background: Interleukin-1 (IL-1), an important proinflammatory cytokine, is suspected to play a role in chronic fatigue syndrome (CFS). Objective: To evaluate the effect of subcutaneous anakinra versus placebo on fatigue severity in female patients with CFS. Design: Randomized, placebo-controlled trial from July 2014 to May 2016. Patients, providers, and researchers were blinded to treatment assignment. (ClinicalTrials.gov: NCT02108210). Setting: University hospital in the Netherlands. Patients: 50 women aged 18 to 59 years with CFS and severe fatigue leading to functional impairment. Intervention: Participants were randomly assigned to daily subcutaneous anakinra, 100 mg (n = 25), or placebo (n = 25) for 4 weeks and were followed for an additional 20 weeks after treatment (n = 50). Measurements: The primary outcome was fatigue severity, measured by the Checklist Individual Strength subscale (CIS-fatigue) at 4 weeks. Secondary outcomes were level of impairment, physical and social functioning, psychological distress, and pain severity at 4 and 24 weeks. Results: At 4 weeks, 8% (2 of 25) of anakinra recipients and 20% (5 of 25) of placebo recipients reached a fatigue level within the range reported by healthy persons. There were no clinically important or statistically significant differences between groups in CIS-fatigue score at 4 weeks (mean difference, 1.5 points [95% CI, -4.1 to 7.2 points]) or the end of follow-up. No statistically significant between-group differences were seen for any secondary outcome at 4 weeks or the end of follow-up. One patient in the anakinra group discontinued treatment because of an adverse event. Patients in the anakinra group had more injection site reactions (68% [17 of 25] vs. 4% [1 of 25]). Limitation: Small sample size and wide variability in symptom duration; inclusion was not limited to patients with postinfectious symptoms. Conclusion: Peripheral IL-1 inhibition using anakinra for 4 weeks does not result in a clinically significant reduction in fatigue severity in women with CFS and severe fatigue. Primary Funding Source: Interleukin Foundation and an independent donor who wishes to remain anonymous.

IL-32γ promotes the healing of murine cutaneous lesions caused by Leishmania braziliensis infection in contrast to Leishmania amazonensis.

Abstract: Interleukin 32 (IL-32) is a pro-inflammatory cytokine induced in patients with American tegumentary leishmaniasis (ATL) caused by Leishmania braziliensis. Here, we investigated whether IL-32 is also expressed in patient lesions caused by L. amazonensis. In addition, we evaluated experimental L. amazonensis and L. braziliensis infections in C57BL/6 transgenic mice for human IL-32γ (IL-32γTg) in comparison with wild-type (WT) mice that do not express the IL-32 gene. Human cutaneous lesions caused by L. amazonensis express higher levels of IL-32 than healthy control skin. In mice, the presence of IL-32γ promoted the control of cutaneous lesions caused by L. braziliensis, but not lesions caused by L. amazonensis in an ear dermis infection model. In addition, IL-32γTg mice displayed less tissue parasitism and inflammation in IL-32γTg than WT mice during the healing phase of L. braziliensis infection. Production of antigen-specific pro-inflammatory cytokines was higher in IL-32γTg mice than in WT mice during L. braziliensis infection but not during L. amazonensis infection. Human cutaneous lesions caused by L. amazonensis express high levels of IL-32. In mice, the presence of IL-32γ contributes to the lesion healing caused by L. braziliensis but not by L. amazonensis. Data suggest that despite the ability for both species to induce IL-32 in humans, the connections between this cytokine and other immune players induced by related species of parasites can lead to distinct outcomes of the murine infections.

Human Alpha-1-Antitrypsin (hAAT) therapy reduces renal dysfunction and acute tubular necrosis in a murine model of bilateral kidney ischemia-reperfusion injury

Abstract: Several lines of evidence have demonstrated the anti-inflammatory and cytoprotective effects of alpha-1-antitrypsin (AAT), the major serum serine protease inhibitor. The aim of the present study was to investigate the effects of human AAT (hAAT) monotherapy during the early and recovery phase of ischemia-induced acute kidney injury. Mild renal ischemia-reperfusion (I/R) injury was induced in male C57Bl/6 mice by bilateral clamping of the renal artery and vein for 20 min. hAAT (80 mg/kg, Prolastin®) was administered daily intraperitoneally (i.p.) from day -1 until day 7 after surgery. Control animals received the same amount of human serum albumin (hAlb). Plasma, urine and kidneys were collected at 2h, 1, 2, 3, 8 and 15 days after reperfusion for histological and biochemical analysis. hAAT partially preserved renal function and tubular integrity after induction of bilateral kidney I/R injury, which was accompanied with reduced renal influx of macrophages and a significant decrease of neutrophil gelatinase-associated lipocalin (NGAL) protein levels in urine and plasma. During the recovery phase, hAAT significantly decreased kidney injury molecule-1 (KIM-1) protein levels in urine but showed no significant effect on renal fibrosis. Although the observed effect size of hAAT administration was limited and therefore the clinical relevance of our findings should be evaluated carefully, these data support the potential of this natural protein to ameliorate ischemic and inflammatory conditions.

IL-32 promoter SNP rs4786370 predisposes to modified lipoprotein profiles in patients with rheumatoid arthritis.

Abstract: Patients with rheumatoid arthritis (RA) are at higher risk of developing cardiovascular diseases (CVD). Interleukin (IL)-32 has previously been shown to be involved in the pathogenesis of RA and might be linked to the development of atherosclerosis. However, the exact mechanism linking IL-32 to CVD still needs to be elucidated. The influence of a functional genetic variant of IL-32 on lipid profiles and CVD risk was therefore studied in whole blood from individuals from the NBS cohort and RA patients from 2 independent cohorts. Lipid profiles were matched to the specific IL-32 genotypes. Allelic distribution was similar in all three groups. Interestingly, significantly higher levels of high density lipoprotein cholesterol (HDLc) were observed in individuals from the NBS cohort and RA patients from the Nijmegen cohort homozygous for the C allele (p = 0.0141 and p = 0.0314 respectively). In contrast, the CC-genotype was associated with elevated low density lipoprotein cholesterol (LDLc) and total cholesterol (TC) in individuals at higher risk for CVD (plaque positive) (p = 0.0396; p = 0.0363 respectively). Our study shows a functional effect of a promoter single-nucleotide polymorphism (SNP) in IL32 on lipid profiles in RA patients and individuals, suggesting a possible protective role of this SNP against CVD.

IL-37 Causes Excessive Inflammation and Tissue Damage in Murine Pneumococcal Pneumonia.

Abstract: Streptococcus pneumoniae infections can lead to severe complications with excessive immune activation and tissue damage. Interleukin-37 (IL-37) has gained importance as a suppressor of innate and acquired immunity, and its effects have been therapeutic as they prevent tissue damage in autoimmune and inflammatory diseases. By using RAW macrophages, stably transfected with human IL-37, we showed a 70% decrease in the cytokine levels of IL-6, TNF-α, and IL-1β, and a 2.2-fold reduction of the intracellular killing capacity of internalized pneumococci in response to pneumococcal infection. In a murine model of infection with S. pneumoniae, using mice transgenic for human IL-37b (IL-37tg), we observed an initial decrease in cytokine expression of IL-6, TNF-α, and IL-1β in the lungs, followed by a late-phase enhancement of pneumococcal burden and subsequent increase of proinflammatory cytokine levels. Additionally, a marked increase in recruitment of alveolar macrophages and neutrophils was noted, while TRAIL mRNA was reduced 3-fold in lungs of IL-37tg mice, resulting in necrotizing pneumonia with augmented death of infiltrating neutrophils, enhanced bacteremic spread, and increased mortality. In conclusion, we have identified that IL-37 modulates several core components of a successful inflammatory response to pneumococcal pneumonia, which lead to increased inflammation, tissue damage, and mortality.

The Effects of Selective Hematopoietic Expression of Human IL-37 on Systemic Inflammation and Atherosclerosis in LDLr-Deficient Mice.

Abstract: The human cytokine interleukin (IL)-37 has potent anti-inflammatory capacities, and hematopoietic cell-specific transgenic overexpression of IL-37 in mice protects against septic shock and colitis. In the present study we investigated the effect of hematopoietic expression of IL-37 on atherosclerosis development under low-grade inflammatory conditions. Low-density lipoprotein receptor (LDLr)-deficient mice were lethally irradiated and transplanted with bone marrow from IL-37-transgenic or control wild-type mice and fed a Western-type diet (WTD; 1% cholesterol) for eight weeks. Metabolic and inflammatory parameters were monitored and atherosclerosis was assessed in the aortic valve area. Hematopoietic IL-37 expression did not influence body weight, food intake and plasma cholesterol levels during the study. Plasma soluble E-selectin levels were increased with WTD-feeding as compared to chow-feeding, but were not influenced by IL-37 expression. IL-37 expression reduced the inflammatory state as indicated by reduced white blood cell counts and by reduced basal and lipopolysaccharide-induced cytokine response by peritoneal macrophages ex vivo. IL-37 expression did not influence the atherosclerotic lesion area. Lesion composition was marginally affected. Smooth muscle cell content was decreased, but macrophage and collagen content were not different. We conclude that under low-grade inflammatory conditions, hematopoietic IL-37 expression reduces the inflammatory state, but does not influence atherosclerosis development in hyperlipidemic LDLr-deficient mice.

Implication of the intestinal microbiome as a potential surrogate marker of immune responsiveness to experimental therapies in autoimmune diabetes.

Abstract: Type 1 diabetes (T1D) is an autoimmune proinflammatory disease with no effective intervention. A major obstacle in developing new immunotherapies for T1D is the lack of means for monitoring immune responsiveness to experimental therapies. The LEW1.WR1 rat develops autoimmunity following infection with the parvovirus Kilham rat virus (KRV) via mechanisms linked with activation of proinflammatory pathways and alterations in the gut bacterial composition. We used this animal to test the hypothesis that intervention with agents that block innate immunity and diabetes is associated with a shift in the gut microbiota. We observed that infection with KRV results in the induction of proinflammatory gene activation in both the spleen and pancreatic lymph nodes. Furthermore, administering animals the histone deacetylase inhibitor ITF-2357 and IL-1 receptor antagonist (Anakinra) induced differential STAT-1 and the p40 unit of IL-12/IL-23 gene expression. Sequencing of bacterial 16S rRNA genes demonstrated that both ITF-2357 and Anakinra alter microbial diversity. ITF-2357 and Anakinra modulated the abundance of 23 and 8 bacterial taxa in KRV-infected animals, respectively, of which 5 overlapped between the two agents. Lastly, principal component analysis implied that ITF-2357 and Anakinra induce distinct gut microbiomes compared with those from untreated animals or rats provided KRV only. Together, the data suggest that ITF-2357 and Anakinra differentially influence the innate immune system and the intestinal microbiota and highlight the potential use of the gut microbiome as a surrogate means of assessing anti-inflammatory immune effects in type 1 diabetes.

Gp96 Peptide Antagonist gp96-II Confers Therapeutic Effects in Murine Intestinal Inflammation.

Abstract: Background: The expression of heat shock protein gp96 is strongly correlated with the degree of tissue inflammation in ulcerative colitis and Crohn’s disease, leading us to the hypothesis that inhibition of expression via gp96-II peptide prevents intestinal inflammation. Methods: We employed daily injections of gp96-II peptide in two murine models of intestinal inflammation, the first resulting from five daily injections of IL-12/IL-18, the second via a single intra-rectal application of TNBS (2,4,6-trinitrobenzenesulfonic acid). We also assessed the effectiveness of gp96-II peptide in murine and human primary cell culture. Results: In the IL-12/IL-18 model, all gp96-II peptide treated animals survived until day 5, whereas 80% of placebo-injected animals died. Gp96-II peptide reduced IL-12/IL-18-induced plasma IFNγ by 89%, IL-1β by 63%, IL-6 by 43% and TNF by 70% compared to controls. The clinical assessment Disease Activity Index (DAI) of intestinal inflammation severity was found to be significantly lower in the gp96-II treated animals when compared to vehicle injected mice. Gp96-II peptide treatment in the TNBS model limited weight loss to 5% on day 7 compared with prednisolone treatment whereas placebo-treated animals suffered a 20% weight loss. Histological disease severity was reduced equally by prednisolone (by 40%) and gp96-II peptide (35%). Mice treated with either gp96-II peptide or prednisolone exhibited improved endoscopic scores compared with vehicle-treated control mice: vascularity, fibrin, granularity, and translucency scores were reduced by up to 49% by prednisolone and by up to 30% by gp96-II peptide In vitro, gp96-II peptide reduced TLR2-, TLR4- or IL-12/IL18-induced cytokine expression in murine splenocytes, with declines in constitutive IL-6 (54%), LPS-induced TNF (48%) and IL-6 (81%), and in Staphylococcus epidermidis (St. epi.)-induced TNF (67%) and IL-6 (81%), as well as IL-12/IL-18-induced IFNγ (75%). Gp96-II peptide reduced IL 1β, IL-6, TNF, and GM-CSF in human peripheral blood mononuclear cells (PBMC) to a similar degree without affecting cell-viability, whereas RANTES, IL-25, and MIF were 2-3-fold increased. Conclusion: Gp96-II peptide protects against murine intestinal inflammation by regulating inflammation in vivo and in vitro, pointing to its promise as a novel treatment for inflammatory bowel disease.

OP0090 The human safe NLRP3 inflammasome inhibitor OLT1177 suppresses joint inflammation in murine models of experimental arthritis

Abstract: Background NLRP3 is an essential component of the inflammasome, an intracellular macromolecular complex, which activates caspase-1 for the processing and release of active IL-1β and IL-18. Activation of the NLRP3 inflammasome takes place in inflammatory joint diseases, including gout. Although inhibition of IL-1β with either the IL-1 receptor antagonist anakinra or canakinumab, a neutralizing monoclonal antibody for IL-1β is highly effective for reducing the gout flares, a clinical need remains for a safe, oral treatment of recurrent gout flares refractory to standard of care. The small orally active and safe β-sulfonyl nitrile molecule OLT1177 is a specific inhibitor of the NLRP3 inflammasome, and currently being evaluated in a Phase 2 study for the treatment of acute gout flares. Objectives To investigate the anti-inflammatory effect of NLRP3 inflammasome inhibitor OLT1177 in mouse models of acute joint inflammation. Methods Two models of experimental arthritis were used in mice: zymosan- and monosodium urate (MSU)-induced arthritis. Knee joints of male C57BL/6 mice were injected intraarticularly with 180 μg heat-killed Zymosan or 300 μg of monosodium urate (MSU) crystals mixed with 200 μM C16.0 fatty acid and bovine serum albumin. Joints were assessed 24 and 4 hours after the zymosan or MSU/C16.0 injection, respectively, for clinical, histological and cytokine analyses. Results Intraarticular Zymosan induced a severe joint swelling with neutrophil infiltration, high levels of synovial IL-1β, IL-6 and the neutrophil chemokine CXCL1. Treatment with OLT1177 induced reduction of joint swelling and neutrophil infiltration (P Conclusions The orally active molecule OLT1177 is a potent inhibitor of IL-1β-driven inflammatory arthritis, particularly in a model of acute gout. Considering the outstanding safety profile in humans, OLT1177 is a potential therapeutic strategy to target NLRP3-driven IL-1β-mediated disorders. Disclosure of Interest C. Marchetti: None declared, B. Swartzwelter: None declared, M. Koenders: None declared, C. Dinarello Grant/research support from: Charles A. Dinarello serves on the Scientific Advisory Board of Olatec and receive compensation, L. Joosten Grant/research support from: Leo A. B. Joosten serves on the Scientific Advisory Board of Olatec and receive compensation

Abstract 18066: Novel NLRP3 Inflammasome Inhibitor OLT1177 Reduces Infarct Size in a Mouse Model of Myocardial Ischemia Reperfusion Injury

Abstract: Introduction: Activation of the NLRP3 inflammasome during acute myocardial infarction (AMI) mediates further inflammatory injury after reperfusion. Several NLRP3 inflammasome inhibitors have been s...